1. Field of the Invention
The present invention relates to a servo control system, and in particular relates to a servo control system that has the function of measuring the characteristic of a learning controller.
2. Description of Related Art
In recent years, techniques related to learning control have been in practical use in machine tools. The learning control is, in brief, a control that optimizes a feedforward signal with respect to certain repeated operations. By performing the same operations in a repeated manner, the feedforward signal is updated and finally converges to a certain form. Learning is ended at that point in time, and the feedforward signal obtained by the learning control is used as is without update.
The principle of high accuracy control of repeated operations using a learning control is reported (for example, Tadashi Inoue et al.: High Accuracy Control of Play-Back Servo Systems, the Institute of Electrical Engineers of Japan. C, Vol. 101, No. 4, pp. 89-96, (1981), hereinafter called “non-patent document 1”). In the non-patent document 1, an evaluation function itself is derived. However, non-patent document 1 does not describe the technique of measuring a frequency response of servo systems and an experimental modal analysis, and hence calculates only a nominal characteristic.